Add tarball signing to Makefile
Add tarball signing to Makefile

I managed to screw up the 3.13 signature doing it manually; the .asc file
contained a copy of the tarball data rather than being *just* the signature.

Add it to the Makefile and that should stop me screwing it up later.

Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

don-johnny/openconnect,mveplus/openconnect-client,mtmiller/openconnect,brandt/openconnect,chadcatlett/openconnect,mveplus/openconnect-client,brandt/openconnect,matlockx/openconnect,mveplus/openconnect-client,mtmiller/openconnect,matlockx/openconnect,atyndall/openconnect,matlockx/openconnect,liiir1985/openconnect,neshema/openconnect,sihde/openconnect,sihde/openconnect,don-johnny/openconnect,don-johnny/openconnect,mtmiller/openconnect,lins05/openconnect,lins05/openconnect,cernekee/openconnect,cernekee/openconnect,certik/openconnect,matlockx/openconnect,don-johnny/openconnect,nmav/openconnect-mine,atyndall/openconnect,chadcatlett/openconnect,neshema/openconnect,mtmiller/openconnect,lins05/openconnect,atyndall/openconnect,brandt/openconnect,liiir1985/openconnect,mdutton3/OpenConnect,mdutton3/OpenConnect,certik/openconnect,chadcatlett/openconnect,cernekee/openconnect,certik/openconnect,lins05/openconnect,atyndall/openconnect,cernekee/openconnect,nmav/openconnect-mine,nmav/openconnect-mine,neshema/openconnect,chadcatlett/openconnect,nmav/openconnect-mine,brandt/openconnect,neshema/openconnect,sihde/openconnect,liiir1985/openconnect,mdutton3/OpenConnect,mveplus/openconnect-client,liiir1985/openconnect